Echoes of Malice by J. Michael Boucher

The sleepy rural town of Franklin is stunned when District Attorney Dennis Archer is brutally assaulted, and a disgraced former mayor with ties to a drug cartel is found dead in his jail cell. Ex-cop-turned-Mayor Matt Riley vows to nail his friend Archer’s assailant, even as he’s haunted by demons from his past and hunted by a drug cartel that has targeted him for assassination. As the investigation unfolds, the cartel floods the town with a deadly new opioid.

Events come to a head when a psychiatrist reveals that Archer’s assailant is her patient but refuses to provide an identity. A final high-tech clue reveals the assailant’s shocking identity just as a deranged hacker crashes the local electric grid and plunges the region into darkness. Amidst the chaos, a police officer corners the assailant in Bandstand Park; only one of them will leave alive.